Hydraulic press with box- and column-type frame

ABSTRACT

A hydraulic power press has a box-shaped frame whose top defines a work space with a bedplate received in that frame, the frame bottom being rigid with a hydraulic cylinder whose piston carries the bedplate. Frame and cylinder are interconnected by columns guiding the bedplate within the frame. The piston has a downwardly projecting rod terminating in an annular flange forming a shoulder which coacts with a set of plungers within the cylinder adapted to be pressurized for moving the piston with the bedplate downwardly. The upper limit of the working stroke of the piston is defined by a rotatable ring threadedly engaging the lower end of the cylinder to form an adjustable abutment for the piston flange. The lower limit of the return stroke is determined by a stud, projecting downwardly from the piston, which on descending coacts with the body of a slide valve whose mounting is fixedly suspended from the cylinder and which, besides cutting off the flow of pressure fluid to the downwardly acting plungers, also cushions the descent of the piston. The stud is threadedly lodged in the piston and can be rotated by a bevel-gear transmission inside the bedplate and the piston for adjusting the lower end of the piston stroke.

United States Patent [191 Nowak [451 Feb. 26, 1974 HYDRAULIC PRESS WITH BOX- AND COLUMN-TYPE FRAME [75] Inventor: Edmund Nowak, Warszawa, Poland [73] Assignee: Przedsiebiorstwo Doswiadczalne Pras Automatycznych i Tlocznikow Ponar-Hydomat", Warsaw, Poland Filed: Dec. 23, 1971 App]. No.: 211,280

US. Cl. 100/257, 100/269 Int. Cl B30b 1/32 Field of Search 100/240, 229, 257, 269

References Cited UNITED STATES PATENTS 2/1950 Hathaway et al. 100/240 3/1950 Barrickman l00/240 X 5/l969 Ozeki et al 100/229 R 7/l969 Brolund [00/229 R X 8/1969 Grantham 100/229 R UX Primary Examiner-William 1. Price Assistant Examiner-Arthur 0. Henderson Attorney, Agent, or Firm--Karl F. Ross; Herbert Dubno 5 7 ABSTRACT A hydraulic power press has a box-shaped frame whose top defines a work space with a bedplate received in that frame, the frame bottom being rigid with a hydraulic cylinder whose piston carries the bedplate. Frame and cylinder are interconnected by columns guiding the bedplate within the frame. The piston has a downwardly projecting rod terminating in an annular flange forming a shoulder which coacts with a set of plungers within the cylinder adapted to be pressurized for moving the piston with the bedplate downwardly. The upper limit of the working stroke of the piston is defined by a rotatable ring threadedly engaging the lower end of the cylinder to form an adjustable abutment for the piston flange. The lower limit of the return stroke is determined by a stud, projecting downwardly from the piston, which on descending coacts with the body of a slide valve whose mounting is fixedly suspended from the cylinder and which, besides cutting off the flow of pressure fluid to the downwardly acting plungers, also cushions the descent of the piston. The stud is threadedly lodged in the piston and can be rotated by a bevel-gear transmission inside the bedplate and the piston for adjusting the lower end Q FDSP QEEKQEE-.,

8 Claims, 2 Drawing Figures PATENTEBFEBZISIQH SHEET 2 0F 2 Edmund NOWAK INVENTOR ATTORNEY HYDRAULIC PRESS WITH BOX- AND COLUMN-TYPE FRAME My present invention relates to a hydraulic power press.

In conventional press construction a work space is provided above a bedplate which is vertically guided between the top and the bottom of a box-shaped frame and which carries a forming tool. Such presses are usually relatively massive and provided with two or more pairs of large-diameter columns for the guidance of the bedplate in order to prevent objectionable deformations. This is so because of the substantial tensile stresses which the frame itself and the columns must sustain in the operation of the press.

An object of my present invention is to provide a more compact power press of this general type which nevertheless is highly resistant to torque and bending stresses.

Another object is to provide a simplified driving mechanism for the bedplate of such a press.

A further object is to provide conveniently operable means in such a press for adjusting the lower limit of the downward or opening stroke of the bedplate, e.g. for the purpose of giving access to a defective tool which is to be repaired.

It is also an object of my invention to provide effective means for cushioning the arrival of the bedplate in its bottom position, the same means serving to cut off the supply of hydraulic fluid which drives the bedplate downwardly.

A power press according to my present invention comprises a hydraulic cylinder below its bedplate, the cylinder being rigid with the bottom plate of the press frame and having a wall provided with an array of vertical bores; a piston in the cylinder, rigid with the bedplate, has a downwardly projecting extremity provided with a peripheral shoulder engaged by a set of vertically movable plungers in the array of cylinder bores. Upon the hydraulic elevation of the bedplate into a working position and the subsequent admission of pressure fluid (oil) into these bores above their plungers to start the position on its downstroke, a slide valve in the path of the piston is engaged by same in its lower limiting position to arrest the descent of the bedplate by cutting off the fluid pressure in the bores. The engagement of the slide valve by the piston also cushions the impact resulting from the halting of its downstroke.

The valve may be carried on a stationary support secured to the cylinder while the piston has an adjustable valve-engaging extension enabling a variation of the lower limit of its descending stroke. This extension may comprise a stud threadedly received in an axial bore of the piston and coupled with a vertical shaft in that bore which can be rotated through a set of bevel gears from a horizontal shaft lodged in the bedplate. The upstroke of the piston can be limited by adjustable abutment means engageable from below by the peripheral shoulder coacting with the plungers of the cylinder.

The above and other features of my invention will now be described with reference to the accompanying drawing in which:

FIG. 1 is an elevational view, partly in section, of a press embodying my invention; and

FIG. 2 is a cross-sectional view taken on the line Il-II of FIG. 1.

The press frame, which in FIG. 1 has been partly indicated in broken lines, comprises a box-like structure 3 with a top plate 1 and a bottom plate 6 bracketing a bedplate 4 which is vertically guided by a set of columns 2 traversing that structure; the columns are fastened to the frame by nuts 26. Bottom plate 6 has a central opening receiving the upper end of a hydraulic cylinder 22, the latter having a peripheral flange bearing upon the underside of that plate unto which it is held by the columns 2. Bushings 5 surround the columns 2 to facilitate the sliding of bedplate 4 therealong.

Cylinder 22 contains a piston 23 threadedly secured to the bedplate 4, its piston rod 8 projecting downwardly from the cylinder and carrying at its lower end a buffer 15 overlain by a bumper plate 16. The piston and its rod are guided in cylinder 22 by annular bushings 21 and 24 providing peripheral clearance between these members. A seal 19 insures fluidtight contact between the piston and the cylinder.

The lower part of the cylinder is formed with an array of vertical bores 30 accommodating respective plungers 20 whose downwardly projecting extremities bear upon the bumper plate 16. Each bore 30 communicates at its top with an inlet 31 to which pressure fluid may be admitted as indicated by an arrow P. The lower end of cylinder 22 is externally threaded and surrounded by a complementarily threaded ring 18 forming an abutment for bumper plate 16 in an upper limiting position of the piston 23. This position can be adjusted with the aid of a worm 17 in engagement with mating teeth on the outer periphery of ring 18.

Bedplate 4 has a lateral bore 31 accommodating a horizontal shaft 25 which, via bevel gears 33, is drivingly coupled with a vertical shaft 7 passing through an axial bore 34 of piston 23. The lower, widened part of bore 34 is in screw-threaded engagement with a stud 10 which is drivingly coupled with shaft 7 so as to form an axially adjustable downward extension of piston 23. A three-way slide valve 13, mounted in a boss 12 of a fixed stop plate 11, lies in the path of the descending stud 10; stop plate 12 is suspended by bolts 9 from cylinder 22 and is provided with conduits 14 through which oil (arrow P) can be admitted to a port of valve 13.

In operation, piston 23 and bedplate 4 are elevated into a working position by the introduction of oil into the cylinder 22, underneath the piston head, under the control of a nonillustrated valve. This results in the shaping of a workpiece by a tool carried on the bedplate 4. With bumper plate 16 now contacting the abutment ring 18, oil is admitted via inlets 31 into bores 30 ,to exert pressure through the plungers 22 upon the plate 16 so that the piston 23 begins to descend. In the terminal phase of this downstroke, the stud 10 strokes the slider of valve 13 to stop the inflow of oil into the bores 13; this action also helps absorb the shock of arresting the piston stroke. The limits of this stroke can be adjusted with the aid of worm 17 and shaft 25.

I claim: 1. A hydraulic power press comprising: a frame provided with a top plate and a bottom plate; a vertically movable bedplate in said frame defining a work space with said top plate; a hydraulic cylinder below said bedplate rigid with said bottom plate, said cylinder having a wall provided with an array of vertical bores;

a piston in said cylinder rigid with said bedplate, said piston having a downwardly projecting extremity provided with a peripheral shoulder;

a set of vertically movable plungers in said bores bearing upon said shoulder, said bores being provided above said plungers with inlets for a pressure fluid; and

valve means in the path of said piston engageable by same upon downward movement thereof under pressure of said fluid for cutting off the fluid pressure in said bores to arrest the descent of said piston from a working position into which the piston has been hydraulically elevated.

2. A power press as defined in claim 1 wherein said valve means is provided with a stationary support secured to said cylinder, said piston being provided with an adjustable extension engageable with said valve means for varying the lower limit of its descending stroke.

3. A power press as defined in claim 2 wherein said extension comprises a stud threadedly received in an axial bore of said piston, further comprising mechanism in said axial bore accessible through said bedplate for rotating said stud.

4. A power press as defined in claim 3 wherein said mechanism comprises a vertical shaft in said axial bore, a horizontal shaft in said bedplate and a set of bevel gears interconnecting said shafts.

5. A power press as defined in claim 1 wherein said cylinder is provided with adjustable abutment means engageable from below by said shoulder for limiting the rising stroke of said piston.

6. A power press as defined in claim 5 wherein said abutment means comprises a peripheral ring threadedly engaging said cylinder and drive means for rotating said ring.

7. A power press as defined in claim 6 wherein said ring is provided with external gear teeth, said drive means comprising a worm in engagement with said gear teeth.

8. A power press as defined in claim 1 wherein said cylinder has a land engaging said bottom plate from below, further comprising a set of columns traversing said top plate, said bottom plate and said land, said columns being provided with screw heads for holding said cylinder onto said frame, said bedplate being slidably guided along said columns. 

1. A hydraulic power press comprising: a frame provided with a top plate and a bottom plate; a vertically movable bedplate in said frame defining a work space with said top plate; a hydraulic cylinder below said bedplate rigid with said bottom plate, said cylinder having a wall provided with an array of vertical bores; a piston in said cylinder rigid with said bedplate, said piston having a downwardly projecting extremity provided with a peripheral shoulder; a set of vertically movable plungers in said bores bearing upon said shoulder, said bores being provided above said plungers with inlets for a pressure fluid; and valve means in the path of said piston engageable by same upon downward movement thereof under pressure of said fluid for cutting off the fluid pressure in said bores to arrest the descent of said piston from a working position into which the piston has been hydraulically elevated.
 2. A power press as defined in claim 1 wherein said valve means is provided with a stationary support secured to said cylinder, said piston being provided with an adjustable extension engageable with said valve means for varying the lower limit of its descending stroke.
 3. A power press as defined in claim 2 wherein said extension comprises a stud threadedly received in an axial bore of said piston, further comprising mechanism in said axial bore accessible through said bedplate for rotating said stud.
 4. A power press as defined in claim 3 wherein said mechanism comprises a vertical shaft in said axial bore, a horizontal shaft in said bedplate and a set of bevel gears interconnecting said shafts.
 5. A power press as defined in claim 1 wherein said cylinder is provided with adjustable abutment means engageable from below by said shoulder for limiting the rising stroke of said piston.
 6. A power press as defined in claim 5 wherein said abutment means comprises a peripheral ring threadedly engaging said cylinder and drive means for rotating said ring.
 7. A power press as defined in claim 6 wherein said ring is provided with external gear teeth, said drive means comprising a worm in engagement with said gear teeth.
 8. A power press as defined in claim 1 wherein said cylinder has a land engaging said bottom plate from below, further comprising a set of columns traversing said top plate, said bottom plate and said land, said columns being provided with screw heads for holding said cylinder onto said frame, said bedplate being slidably guided along said columns. 